Apparatus for deflecting bore holes



I i L! A. F. PICKARD June 3, 1958 APPARATUS FOR DEFLECTING BORE nounsFiled/Aug. 16, 1954 F/GJ UNIVERSAL Jo/zvr June 3, 1958 A. F. PICKARDAPPARATUS FOR DEFLECTING BORE HOLES 2 Sheets-Sheet 2 Filed Aug. 16, 1954MV/I/ERSAL Jam/r 24 INVENTOR. 4485/? TEp/C/(ARD I MW ATTORNE Y6 StatesLongyear Company, Minneapolis, Minn., a corporation of DelawareApplication August 16, 1954, Serial No. 449,942

6 Claims. (Cl. 2551.6)

This invention relates to the art of well drilling. More particularly,this invention relates to an improved apparatus for deflecting boreholes.

It is the principal object of this invention to provide improved methodsand apparatus for deflecting the direction of bore holes. in sub-surfaceformations.

Another object of this invention is to provide an improved method andapparatus for returning angular bore holes to a more verticalorientation.

It is still another object of this invention to provide an improvedmethod and apparatus for deflecting bore holes in predetermineddirection and angles.

A further object of this invention is to provide an improved method andapparatus for deflecting bore holes in sub-surface formations withoutthe use of wedges, whipstocks and the like.

Other objects of this invention will become apparent,

as the description proceeds.

To the accomplishment of the foregoing and related ends, this inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description setting forth indetail certain illustrative embodiments of the invention, these beingindicative, however, of but a few of the various ways in which theprinciples of the invention may be employed.

The invention is illustrated with reference to the drawings in whichcorresponding numerals indicate the same parts and in which:

Figure l is a fragmentary sectional view, which may be alongitudinalsection illustrating a sub-surface formation with a normal rotary corebit and a'reaming shell therein at the bottom of a hole produced by thebit;

Figure 2 is a similar View showing in section the appearance of the holeafter removal of the core drill and core sample;

Figure 3 is a sectional view of the same bore hole showing the bottom ofthe hole squared and the apparatus of this invention set in place tobegin drilling a pilot hole;

Figure 4 is a sectional View showing the apparatus of this invention inplace of the new and deflectedpilot hole;

Figure 5 is a sectional view of the new and deflected bore hole reamedto size;

Figure 6 is a sectional view of a sub-surface formation showing one formof apparatus of this invention, partly in section, in place in the borehole; and

Figure 7 is a transverse sectional view taken along the line 7-7 and inthe direction of the arrows of- Figure 6, but oriented, with relation tothe rotation axis differently than in Figure 6.

Referring to the drawings, a sub-surface formation is illustrated at 10in Figure l and in the remaining figures. The sub-surface formation maybe considered as being deep in the rock forming the earths crust and maybe considered as being hundreds or thousands of feet from ren t PatentedJune 3, 1958 "ice the. surface where the drill rig is situated. It iswell known, of course, that where drilling is initiated from the surfacethrough the drift or soil overlaying the subsurface rock formations, itis customary to drill through the drift and case the hole thus formeddown to rock level with casing of suitable size so as to prevent cavingthrough the overlaying drift. However, deep in the rock formation thereis usually no casing, the hole wall being maintained by the strength ofthe formation itself. Thus, inFigure 1 the drill rod 11 is in the borehole 12 and at-its lower end may carry a reaming shell at 14 below whichthere is mounted the usual rotary or core bit 15. Although, illustratedwith particular reference to holes drilled with a diamond core drill itis to be understood that the principles of this invention are not solimited but are applicable as well to use in deflectin bore holes, bywhatever means made.

Because the bore holes illustrated in the figures of the drawings are ofconsiderable length, they are necessarily broken, as in Figures 3, 4, 5and 6 in order to show the reference portions of the hole and apparatusin a scale which will be intelligible. Although in sectional view, thesub-surface earth formations have not been hatched since the presence ofthe oblique parallel cross-hatching lines creates optical illusionswhich tend to distort or obscure the deviations of the illustrated boreholes and makes more difficult the understanding of the invention. I

At any depth the drill operator can by suitable instruments and methodswell known in the art deter-- mine the direction and angle in which thehole is progressing. When it is determined that the direction and angleof the drill hole are not such as is desired and the path of furtherdrilling is desired to be deviated from that shown at 16, the directionof drilling must be corrected. In accordance with this invention suchcorrection of drilling direction and angle is accomplished in aplurality of novel manipulative steps and by the use of novel.combinations of apparatus as follows:

The invention will first be described with reference to deflecting aninclined bore hole to a vertical direction. The fact that the bore holehas deviated from vertical becomes known by means of a survey of thehole for angle and direction (azimuth).

Although members 11 are actually tubes screwed together they arecommonly referred to as drill rods and collectively when assembled endto end in a hole as a drill string. This terminology will be usedthroughout this specification. discussion the drill string may include acore barrel 11a on the end of the lowermost drill rod 11, as is commonlyused in exploratory drilling. The entire drill string is providedthroughout its length with a central aperture 17 through which drillingfluids under pressure are pumped from the surface for the purpose oflubricating and cooling the bit and carrying cuttings up around thedrill string to the surface.

As is well understood in this art, the .drill stringshould be centeredin the bore hole at all times in order stabilizers or guides areconventionally used in the Obviously, the diameter of the drill stringmust be smaller than that of the hole, but otherwise it is inde- For thepurpose of this 3 pendent of the diameter of the bore hole and of thediameter of the pilot drill.

As shown in Figure 2, when the drill string with the core bit is removedfrom bore hole 12, the bottom 18 of the bore hole is irregular incontour, usually containing a stump 19 of the core. The :first step .inpreparing the hole for deflecting its course isltoasquare or flatten thebottom of the hole by grindin'g it out by well known conventional meansand (as-shown-in Figure 3) providing the hole with a new bottom 18A. Thecore bit 15 and reaming shell 14 are removedfrom the bottom of the drillrod '11 and a deflecting pilot drill 'head is substituted therefor.

The deflecting .pilot drill assembly comprises "a pointed diamond roundnose bitZll having a diamond 21 or other hard material point positionedat the apex of the nose to act as-a pivot for the drill. The roundnosedrill pilot bit, which is substantially smaller indiameter than the borehole '12, is mounted on the lower end of an elongated-section of reducedtubular drill rod 22 which is'substantially smaller-in diameter than thebit 20. This thinner drill rod 22 is joined to the core barrel 11a bymeans of a reducing coupling and universal .joint indicateddiagrammatically 'at 24. Fluid channel 17 extends down to the :pilotdrill bit and terminates in one or more :generally'transversefluidejection-ports 25 in .onesideofthe bit=above the pivot diamond.

The following dimensions are illustrative of the relative proportions'ofthe several elements of drilling equipment. given by way of example onlyand do not constitutea limitation upon the invention. Where the drillstring is comprised of size N drill rods 11 and size NX core barrel 11aon the lowest rod 11 the drill rod 22 maybe size E, 5 to6 feet inlength. It may be explainedat this point that N, EQNX, EX, etc. aredesignations of the Diamond Core Drill -Mannfacturers Associationcovering dimensional standards of bits, drill rod and casing. Thestandards are based on "a series of four nesting casings correspondingto which are four sizes of bits, casing and drill rods. 'NX bits and Ndrill rods will pass through NX casing and will=drill a hole largeenough to admit 'BX casing, through which, in turn, a BX bit and Bdrillrod will pass and drill a hole large enou'ghto admit AXcasing,'and--so" on. For convenience represent- 1 ative dimensionsaretabulated below:

Casing Bit-O. D. Rod-O. D.

"o. n. I.D.

Inches Indies Inches EX 1 4e 1% 1%6 AX an 1 its BX 2% 2% 1 952 NX ass 3i 2% The reduced diameter ofthe extension-drill rod permits directingthe-roundnoseibit in a more vertical direction and allows clearancearound the point of juncture of the two holes'as the smaller -bitadvances.

After the bottom of the normal-bore hole12=has'= been squared'orflattened the deflecting-drill assembly is gently lowered tothebottom of the hole and thehole is fluShed thoroughly to removeany-cuttings whichomayi be prescut. The drilling'fluid -is then shut offand=the drill string is then lifted from theybottom of theholea-shortdistance, for example, onefoot or more, and-allowedto hang suspended fora short time-until the pressure of the fluidin the drill string hasequalized with-the -fluidin the bore hole. Normally, this will not takemore-than one or two minutes.

The drill string is then again lowered untilnthe bit touches bottom andseveral hundred pounds pressure is applied on the bit to seat'the' pivotdiamond" of the bit. Because of the 'reduced diameter of'the lower elidofithe his to be understood, however, that they are string the universaljoint 24 permits the deflecting bit .to orient itself .at .the lowestpoint in the bore hole.

That is, under the effects of gravity the lower end of the drill stringtends to bow directing the bit vertically downwardly. In the bore holeillustrated in the drawings the low part of the hole is on the righthand side. The pilot bit will seek out and-seat itself at this pointgenerally as shown in Figure 3.

The drilling fluid .is again turned on and drilling is resumed. Becauseof the seating of the bit on its diamond tip under;pressure the bitpivots on this point and begins drilling a hole in the general directionof the desired path indicated at 27. Without the pivoting axis provided-by the diamond'tip of the bit, the bit would tend to walk aroundthebottom of the hole so that the point at which it would seat itselfand begin drilling could not be predicted.

Drilling with the round nose pilot bit is continued until the newsmaller diameter pilot bore hole 28 approachesa idepth corresponding tothe length of the extension drill rod 22, as shown in Figure 4. At thisPOlBLQWhlCh Will-bdOflhfi order of 4 to 5 feet in the case of lt heexemplary dimensions) before the drill string begins to bindin thesmaller hole, the drill string is pulled 'a-n'd the pilot hole'issurveyed for angle and direction. The 'courseof'the pilot hole will notimmediately assume the desired vertical direction but will be bowedlou't wa'rdly slightly from the direction of the former more graduallyassuming the new vertical direction. If the angle and direction of thepilot hole are wron g the hole is reamed'to original size, flattened andthe deflectingcycle to this point is repeated. On the other hand 'ifthe-course of the pilot hole is as planned and desired, then anothersection of small diameter drill rod isjinserted'in the lower end of thedrill string and further drilling of the pilot hole is continued. It maybe -pre'ferre'd at this point to remove the round nose bit andsubstitutein its place a conventional core bit or other bit er correspondingdiameter. In the exemplary situation an size bit may be substituted 'forthe two inch round'nose bit and the small hole may be advanced alongthe=same-path 29 to a further depth of the order of about six additionalfeet. The-hole is then reamed to original size 30 to the bottom, in thecase of the example to NX size.

Depending upon the extent of the original angular deviation of bore hole12 one cycle of the deflecting method may be sufficient to return thecourse of the bore hole to the desired true vertical direction. However,becauseit'is possible to change-the direction of the hole only a fewdegrees in this relatively short distance, if the angular deviation isgreat it may be necessary to repeat the process as described aboveseveral times before the desired deflection is attained, beginning fromthe new bottom 31 of the hole. In the case of the cited example using anAX pilot hole about 10 feet in depth in an NX bore "hole the maximumangular deflection that would normally be attained is about one degree.Greater deflection can be obtained in larger diameter holes.

The apparatus and procedures of this invention may likewise be utilizedto deflect a bore hole in a predetermined direction. For example, a holedrilleddeep into the crust of the earth, intended to follow anorth-northwesterly course at an angle five degrees from the vertical,may'be surveyed and found to be following a course northward from thewell head. In order to return the course of hole to the desireddirection it is necessary that the direction of the hole he deflectedWestward. This maybe done in one of two ways, by orienting the ejectionport 25 deflecting drill 20 with reference to an index point on thesurface or by orientingthe ejection port 25 deflecting drill 20 withreference to an off-center weighted member 34 at the bottom of the hole(see Figs. 6 and 7).

'In' the first of these methods the roundnose pilot drill bit may beoriented with reference to an index point at the surface by means wellknown in this art. For example, an index mark may be placed on eachsection of drill rod 11 as it is attached to the drill string withreference to the master index point at the surface and the index markson each preceding lower drill rod 11. The position of the index mark onthe section of drill rod 11 nearest the bottom of the hole with respectto the index point at the surface can readily be determined. Knowingthis, the extension drill rod 22 and the pilot drill bit 24 areassembled for mounting on the bottom of the drill string. A round nosepilot bit 20 having a single, generally transverse water ejection portis used and is oriented so that the ejection port 25 will be oppositefrom the direction of the desired deflected hole. In the example cited,since it is desired to deflect the course of the hole westward, the bit20 is oriented with its fluid port directed eastward.

After the bottom of the hole has been reamed flat the drill string withthe oriented bit is lowered into the hole. The drilling fluid is turnedon and the hole is cleaned by flushing. The drill string is liftedmomentarily and then lowered. At the bottom of the hole the force-of thejet of drilling fluid being ejected from the port 25 pushes the roundnose pilot bit 20 to the opposite side of the hole. In this instance,since the fluid port is oriented east the bit is forced westward, thedirection of the desired deflection. The bit, while so held, is loweredinto engagement with the bottom 18a of the hole 12 and the pivot diamondis seated to hold the bit 20 from moving transversely, and drilling ofthe deflected pilot hole begins as described above.

Alternatively, the pilot bit is oriented with respect to a weightedmember at the bottom of the hole. In this form of the invention thedrill string is provided at its lower end with an elongated thickenedtubular section weighted on one side and adapted to hang freely at thebottom of the hole so that the weighted side of .the section can seekout and come to rest on the low side of the hole. One form of suchapparatus is shown generally in Figures 6 and 7. The lower extension ofthe drill string comprises the round nosed pilot drill bit 20 with asingle generally transverse water port 25, threaded onto a drill rod 22of lesser diameter than the remainder of the drill string 11 and areducing coupling and universal joint 24 are as previously described.This pilot drill extension assembly is joined by means of a rigidcoupling 33 between the off-center weighted section 34 and coupling 24.This section comprises a length of tubular drill rod 35 weighted on oneside with lead 36 or other suitable heavy substance cast or otherwiseinserted and held in the rod to make one side substantially heavier thanthe other so that under the effects of gravity this heavy side will lielowermost in an inclined hole. The unfilled space 37 on the opposite orlight side of the drill rod forms a channel which maintains direct fluidcommunication through fluid channel 17 of the entire length of the drillstring. The weighted drill rod 34 is affixed to a spline member 38 whichhas an axial opening therethrough. A tubular shaft 39 is aflixed at itslower end in the axial opening of the spline member 38 and extendsupwardly from the spline member. A shaft-suspending coupling 40 iscoupled to the lowest rod member 11 and has a cooperating female splinemember 41 formed therein to mesh with member 38. Shaft 39 extendsthrough and is slidable and rotatable in the axial opening in'thecoupling 40 and has a bearing structure 42 on the upper end thereof. Thesliding movement of the shaft 39 and spline member 38 is limited by aretaining nut 44 locked on the threaded end of shaft 39.

The length of the shaft 39 is suflicient that when the drill string ishanging free in the hole 12, that is, with the bit lifted from thebottom surface 18a, the weighted section 34 causes the cooperating maleand female spline members 38 and 41 to separate sufficiently to permitfree rotation of the weighted member 34, shaft 39, rod 22 and bit 20.This permits the weighted member 34 and bit 20 to rotate by gravity to apredetermined orientation. Thus, by properly orienting the fluid port 25of the pilot bit 20 in relation to weight 36 before lowering it into thehole by means of the shim washers 32, the pilot drill bit 20 will beproperly oriented so that the pilot .hole will be deflected in thepredetermined direction.

respect to the weighted member 34 at the bottom of the hole, the holeafter being surveyed to determine angle and azimuth is flattened at thebottom. Since the direction of the bottom of the hole is known (north inthe assumed example) and it is known that the heavy side 36 of theweighted member 34 will lie adjacent the lower side of the hole (southin this instance), the round nose pilot,

bit is oriented so that the water port 25 opens outwardly in an easterlydirection, or opposite to the direction in which the hole is to bedeflected (west). The assembled drill string containing the-weightedsection 34 and bit 20 is then lowered to the bottom of the hole and thebottom is cleaned by flushing thoroughly. While flushing the drillstring is raised and lowered sufficiently to just lift the round nosedpilot bit a few inches off the surface of the bottom of the hole. Thisnecessarily requires additional lifting of the upper part of the drillstring so as to permit relative sliding movement of the lower drillstring (including the weighted section 34 and pilot drill assembly) withrespect to the remainder of the string. The lower end of the drillstring is then free to rotate on its bearing 42 independently of theremainder of the drill string. The dynamic friction produced by theslight raising and lowering of the drill string in the drilling fluidpermits the heavy side 36 of the weighted section 34 of drill rod to beoriented adjacent the low wall of the bore hole, in the instance of theexample with its index true south. At the same time the action of thejet of fluid from the fluid port 25 in the side of the bit 20 forces thebit to the opposite side wall hole. The bit 20 is lowered to seat thediamond 21 which prevents transverse movement of the bit 20. In the caseof the splined apparatus the drill string is simply lowered until theupper spline member 41 seats upon the lower spline member 38. Since theteeth of the spline are fine, any turning of the weighted section 34 andbit 20 during seating of the spline will be minimized. After the bit isseated on its pivot diamond, drilling of the deflected pilot hole isbegun as described heretofore.

Throughout the foregoing description of the invention it has beenassumed that the bore hole deflection has been started from the naturalbottom of a hole. It is to be understood, however, that the driller mayalways back up and cement a plug in a hole at any desired level and thenusing that plug as a bottom carry on the operation of the invention asdescribed. Hence the bottom 18A of the hole in Figures 3, 4, 5 and 6 maybe considered as a natural formation or as a plug cemented-in at adesired level.

It is apparent that many modifications and variations of the inventionas hereinbefore set forth may be made without departing from the spiritand scope thereof, the specific embodiments described are given by wayof example only, and the invention is limited only by terms of theappended claims.

What I claim is:

1. Apparatus for deflecting bore holes of predetermined 75 diameteradaptedto. be mounted on the lower end of a drill string, said apparatuscomprising a pilot bit having a diameter substantially smaller than thepredetermined diameter of the bore hole, said bit being carried by asection of drill rod having a diameter substantially smaller than thepilot bit, a hard pivot point centrally positioned in the nose of saidhit, an off-center fiuid ejection port in the side wall of said bit,another section of drill rod having one side thereof weighted, universalcoupling means for coupling said smaller drill rod to the weighted drillrod section whereby to permit transverse movement of the bit relative tothe bore hole, and means for coupling said weight ed drill rod sectionto said drill string, said weighted drill rod section being mounted forfree rotary and limited sliding movement with respect to said drillstring, means for engaging said weighted drill rod section for rotarymovement with the drill string and a fluid channel runninglongitudinally through said coupling means, drill rod sections and bitcommunicating with said ejection port.

2. Apparatus according to claim 1 further characterized in that saidpilot bit is a round nose diamond bit and said hard mineral pivot pointis diamond.

3. Apparatus according to claim 1 further characterized in that themeans for mounting said weighted drill rod section for free rotary andlimited sliding movement comprises a tubular shaft, a hanging couplingon the drill string and having an axial opening therein, a tubular shaftslidably and rotatably received in the opening, retaining means forlimiting sliding movement of said shaft, a hearing on said shaft betweenthe coupling and retaining means, and engaging means on said couplingand adapted to. seat in axial movement with cooperating engaging meanson the weighted drill rod section for imparting rotarymovement of thedrill string to the Weighted drill rod section.

4. Apparatus according to claim 3 further characterized in that saidengaging means comprise spline members.

5. Apparatus for deflecting bore holes of predetermined diameter adaptedto be mounted on the lower end of a drill string, said apparatuscomprising: a round nose diamond pilot bit having a diametersubstantially smaller than the predetermined diameter of the bore holecarried by a section of drill rod having a diameter substantiallysmaller than the pilot bit; a diamond pivot point centrally positionedin the nose of said bit and an off-center fluid ejection port in theside wall of said bit; another section of drill rod having one sidethereof weighted; a universal joint coupling said smaller drill rod tothe weighted drill rod section; means for mounting said weighted drillrod section to the drill string for free rotary and limited slidingmovement with respect to said drill string, said means comprising acoupling on the drill string and having an a rial opening therein, atubular shaft slidably and rotatably received in the opening, retainingmeans for limiting sliding movement of the shaft and a bearing on saidshaft between the coupling and retaining means; said shaft being atiixedto the weighted drill rod section; key means on said coupling andcooperating key means on said weighted drill rod section forimpartingrotary movement of the drill string to the weighted drill rod section;and a liuid channel running longitudinally through said coupling means,drill rod sections and bit communicating with the ejection port in saidbit and providing direct fluid communication with s aid'drill string.

6. Apparatus according to claim 5 further characterized inthat'sa'idcooperating key means comprise spline members.

Referencesifited in the file of this patent UNITED STATES PATENTS 92,014Case June 29, 1869 134,506 Ball Jan. 7, 1873 1,902,174 Lewis Mar. 21,1933 2,167,194 Anderson July 25, 1939 2,173,309 Monroe Sept. 19, 1939ENTTEE STATES PATENT OFFICE QETTFTQATE OF CORRECTION Patent Nox2,831,314 June 3, 1958;

Albert FD Pickard It is hereby certified that error appears in theprinted specificatio of the above numbered patent requiring correctionand that the said Letter Patent should read as corrected below.

, Column 3 line 62 for "deflecting" read deflecting column 5 line 23;,for "lowered read m relowered Signed and sealed this 16th day ofSeptember 1958.,

UZBSIZ KARL Ho AXLINE I ROBERT C. WATSON Attesting Oflicer Commissionerof Paten-

